Formation of the rafters and support members for a common pitched roof requires marking rafters at different angles so they can be cut correctly to fit the roof structure. Marks must be made for pitch lines, bird's mouth cuts, notches for ledgers, and other cuts to be made. There are many examples in the prior art of devices to simplify the steps of marking and cutting these rafters and many devices which are capable of more than one or two of the functions required to mark the rafters properly. Examples of such devices can be found in U.S. Pat. Nos. 1,644,624, 4,513,510, 4,598,482, and 5,090,129.
Traditionally, a carpenter cuts out the rafters for a structure using a framing square, a carpenter's tape, a look-up table for the desired pitch from any of several available rafter books, and the zero pitch roof plan from which the run of each rafter is given or can be obtained by measuring the drawing. Although this method can achieve accurate results, it is time consuming and requires a good deal of manipulation of the framing square and addition of the table entries. Each additional step provides another possibility for error. As is explained in U.S. Pat. No. 4,598,482, templates have been created which can replace the framing square. These templates may have a fixed angle that is the desired degree of pitch and therefore does not require continuous manipulation by the user. However, use of such devices may require several templates for different degrees of pitch or may require various adjustments to obtain different pitches. There is a need in the field of rafter marking tools for a device which is easily manipulated to mark the pitch line for a variety of different pitches. Similarly, there is a need for a device which can quickly mark bird's mouth cuts and notches for ledgers.
In construction of a house, a worker will find it necessary to cut or strip sheet rock or other construction materials along a line parallel to one side of the material. In the past, these cuts were made by first measuring twice from the side or straight edge and drawing a line between the two measurements. A cut was then made along the line with a utility knife. This two-stepped method is time-consuming for a worker. Moreover, cutting along a line without a guide may result in uneven lines. There is a need for a better device for cutting the construction material along the line parallel to an edge.
To trim any opening correctly, a carpenter must measure the short and long points for the trim at various intervals along each side of the opening. Lines must be drawn then to connect these measurements. The lines represent the margins for the eventual trim for the opening. This method is slow and invites possible errors if incorrect markings are made. There is a need for a quicker, more accurate means of marking the margins for trim for openings.
Modem architecture has added many arcs in doorways and windows which require drawing of any number of different size arcs before making a cut. Generally, the arcs are drawn by the use of a string, a nail, and a pencil. The nail is driven into the center point of the arc of the circle and the string is extended between the pencil and the nail. The length of the string between the nail and pencil is equal to the radius of the arc. Thus, when the string is taut, the pencil encircles the nail and draws an arc. This method of drawing arcs is slow and may be inaccurate because different angles of the pencil may give different radii, and keeping the string taut while drawing the arc may be difficult. There is a need for a quicker, simpler, and more efficient way of marking the arcs.